Self Build Mortgages > How do they work?
How do Self Build Mortgages work in the UK?
What is a Self Build Mortgage?
A self build mortgage is a specialist type of loan designed for people who are building a home from scratch or carrying out a major renovation or conversion.
Unlike a standard residential mortgage, where you borrow the full amount in one lump sum, a self build mortgage releases money in stages as your project progresses.
There are two main types:
Arrears stage payments: money is released after each stage of work is completed and inspected. This is the most common structure among lenders.
Advance stage payments: money is released at the start of each stage, before the work is completed. This helps with cashflow but is only offered by certain lenders.
Which is best depends on your financial position and project plan. A specialist adviser can guide you on the right fit (like Mayflower!), so you shouldn’t have to make the decision alone.
What do you need in place before applying?
Self build mortgages carry more moving parts than a standard home loan. Lenders will want reassurance that your project is well planned and realistic. Typically, you’ll need:
Planning permission for your build
Land details. Owning land outright can count towards your deposit.
Architect’s drawings and specifications. We offer FREE planning drawings if you’ve got your land.
A detailed cost breakdown of your project. We offer a FREE fully costed schedule of works for all our customers as part of our Self Build Savers Solution.
Builder or contractor agreements. Lenders prefer to see you’re working with professionals.
Proof of finances. Such as your deposit, savings, or equity in land.
Your Self Build Mortgage checklist
There’s lots you’ll have to think about, but that’s why we are here to help guide you through every step of your project with a dedicated adviser.
Here’s just some of the things we can help you to understand or obtain.
✔ Planning permission status
✔ Planning drawings
✔ Detailed cost estimates
✔ Builder details and contracts
✔ Contingency budget
✔ Build schedule timeline
✔ Proof of finance
✔ Insurances and warranties
✔ Risk mitigation plan(s)
✔ Utilities & service provision
✔ Project valuations
✔ Legal checks
✔ Site condition and surveys
Your Self Build timeline
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01. Find and secure land
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02. Obtain planning permission
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03. Arrange your finance (with Mayflower!)
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04. Start construction
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05. Inspections and sign-offs at each stage
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06. Final completion and mortgage conversion
What are the current Self Build Mortgage rates?
At Mayflower Mortgage, we work with specialist lenders to offer some of the most competitive self build mortgage rates in the UK.
See our latest Self and Custom Build Mortgage rates on our dedicated page.
What’s Loan to Value (LTV)?
This is a ratio, shown as a percentage, which represents how much you borrow compared to the value of a property. A lower LTV, which will be because of a large deposit, is generally seen as less risky and so can lead to better mortgage interest rates.
To calculate your LTV:
Determine both your deposit amount and your expected property value.
Subtract your deposit from the property value to get your required loan amount.
Divide the loan amount by the property value.
Multiply the result by 100 to get the percentage.
Many lenders will go up to 75% LTV, or sometimes higher if you have a strong application.
Common Self Build risks to avoid
Costs overrunning
Add contingency funds into your finance plan and use fixed-price contracts where possible.
Cashflow strain
Plan cashflow projections and have savings or other funding ready. Mayflower will be here to help you with this.
Planning or regulation delays
Start planning permission early and understand your local authority timelines as they do differ by location.
Plot issues
Do thorough site surveys and confirm legal title and boundaries way in advance of your project starting.
Design changes during build
Finalise your specification upfront and make sure you lock in any major design decisions before building starts.
Contractor issues
Vet builders carefully and use clear contracts. We are partnered with people who can help you get the right trades at the right time for your project.
Personal financial risks
Maintain some financial reserves and ensure you can still afford the project under different scenarios if things go wrong (delays, interest increases, etc.)
Costs overrunning
Get all required insurance and ensure structural warranties are all correctly in place. We’ll help with this, and making sure everything is disclosed to insurers at the right standards.
Why work with Mayflower Mortgage?
We work with clients across the UK to:
Compare rates from self build lenders on the market
Match you to the lender that best suits your build and budget
Handle the application from start to finish
Give you access to Self Build Saver Solution
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![Winner badge]()
Best Self Build Mortgage Advisory Firm
Design and Build Awards 2025
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![Finalist badge]()
Best Specialist Broker
Finalist at the 2025 Mortgage Strategy Awards
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![Logo of Financial Reporter featuring a blue laurel wreath surrounding the letters 'fr' and the text 'financial | reporter' beneath it.]()
Best Specialist Broker
Finalist at the 2025 Financial Reporter Awards
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![Gold oval badge for the National Custom & Self Build Association (NACSA) indicating support as a Gold Partner for 2024, with website www.nacsba.org.uk.]()
NaCSBA Gold member
National Custom & Self Build Association
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![Grand Designs Live logo with black text and a blue circle containing the word 'LIVE' in white]()
Grand Designs
As seen at Grand Designs Live in London
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![Logo for 'Build It Live' event with the phrases 'Self Build,' 'Home Design,' 'Renovation,' and 'Extension' listed below.]()
BuildIt Live
As seen at BuildIt Live
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![Logo for the Homebuilding & Renovating Show celebrating 30 years from 1994 to 2024, with black, blue, and white text.]()
Homebuilding & Renovating Show
As seen at the Homebuilding & Renovating Show
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![NACFB logo with the tagline "Helping Fund UK Business"]()
NACFB Member
National Association of Commercial Finance Brokers
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![Logo for the Association of Mortgage Intermediaries featuring the acronym 'AMI' in white letters inside blue circles, with the full name written below.]()
AMI Member
Association of Mortgage Intermediaries
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![Logo of the Structural Timber Association with the acronym 'STA', a vertical multicolor line, and the words 'Structural Timber Association Member'.]()
STA
Structural Timber Association Member
Start your Self-Build journey with Mayflower.
At Mayflower, we specialise in self build, renovation, and conversion mortgages. Our dedicated advisers know the challenges (over half of us have been there ourselves) and we guide you through each step so you can focus on building your dream home.
